1. Field of Invention
This invention relates to security devices, and specifically to security devices that mislead potential intruders into thinking that there are occupants at home.
2. Description of Prior Art
Home security is an ongoing concern for nearly everybody. As long as there are people who have homes containing possessions, there are others who would, provided the opportunity, break into those homes to steal those possessions. Alarm systems are available that attempt detection of intruders and, in response, alert the homeowner, a hired security company, or neighbors. However, as long as the intruder believes he has time where he won't be disturbed, he is often able to disable or circumvent the alarm system. In any case, damage can occur before an alarm is sounded.
A better defense against intruders is to deter them from considering entry in the first place. It has been shown that a dog inside the house can be effective in this regard. Not everybody can nor wants to own a dog, though. Also, it is often not feasible to leave a dog alone during extended trips. And, finally, an unrestrained, un-reprimanded dog barking inside can often have the opposite effect—reassuring the desirous intruder that no one is indeed at home.
A proven means for deterring potential intruders is to convince them that someone is at home. U.S. Pat. No. 4,970,489 describes an occupancy simulator that casts shadows on an interior walls which are meant to resemble people walking to and fro within. This patent suffers the failing that the intended simulation of human presence falls woefully short of actual realism. The device described casts shadows that move steadily across the wall with no apparent animation, as though a statue were being dragged back and forth. Additionally, an observer intuitively understands that distinct shadows are cast on a wall by a single, undiffused light source, and that this type of lighting is extremely rare in a modern home, where room lighting is generally provided by recessed ceiling lights, or by lamps or ceiling lights that include shades which specifically diffuse the light in order to eliminate distinct shadows.
U.S. Pat. No. 5,442,524 describes a different approach to the same ends by casting moving shadows across the inside of a shade or curtain. Although the invention attempts to incorporate a certain degree of randomness to the speed of the parade of shadows, the fact that they always move in one direction, and that their shapes remain fixed and inanimate, leave the result to fall far short of a convincing simulation of human movements. Additionally, although the rate of rotation of the generating mechanism is not constant, the shadow patterns still repeat every few minutes, thus betraying the artificial source.
Although it is common to leave lights and even a radio on inside, there are few better indications of occupancy than the distinctive flickering, subtly changing light from an operating television. Some people do indeed leave a visible television on while out for an evening, but this is rarely considered practical for extended absences. Additionally, the televisions may be located in inner rooms where they would not have visible indications from outside.
U.S. Pat. No. 5,252,947 describes a home security device for simulating a television, however, this method lacks substantial ability to convincingly mimic a modern television for multiple reasons. Firstly, the invention describes a flasher for varying the brightness of a light source. These flasher devices enable electricity to flow in an interrupted, semi-regular fashion that, when used with the light source, produce a slow-rhythm strobing effect that might simulate a scene filmed in a discotheque, but is far removed from what is encountered on any normal television broadcast. Even if the flasher device were somehow made to switch on and off in a random manner, this still would not fairly simulate an actual television in operation since a typical television image consists of complex patterns as scenes fade, swell, abruptly change, or slowly transition as the camera pans, resulting in images that thusly fade, swell, flick, and remain nearly steady for varying periods of time.
Secondly, the patent describes a blue light, which is appropriate for a black-and-white television, whereas virtually all modern televisions for home use are color.
Finally, the patent describes an incandescent bulb which is wasteful of energy and could burn out when operated over extended periods of absence.
As is demonstrated in the failings of all of the just-described patents, humans and their activities exhibit both a subtly and a sophistication that is not readily imitated by regular, repetitive actions, whether a flashing light intended to imitate an operating television, or carousel-type shadows moving back and forth across a wall or window covering.
Advantageous would be a device that accurately simulates an operating television that could be easily positioned anywhere in the home.